We set up the Sham EA group as controls and 1-MT, a classical IDO1 inhibitor, as a positive control for the LPS-to-depression pathway is mediated by the activation of the ubiquitous enzyme IDO and increased the production of excitotoxic kynurenine metabolites, including quinolinic acid (QA), in the brain (Shi et al., 2019), thereby directly or indirectly affecting glutamate (Connick and Stone, 1988), leading to neuroexcitatory and neurotoxic properties. This evidence concerns the gene IDO1 and major depressive disorder.